The present invention relates to a sealed rolling bearing comprising an inner and an outer ring, between which is inserted a row of rolling bodies, and a pair of sealing rings, each of which presents at least one radial lip designed to rest and slide on a corresponding surface of the inner ring and is inserted in an annular groove formed on the outer ring.
The said annular groove presents a pair of shoulder surfaces, of which the first is located on the side facing the row of rolling bodies and the second on the opposite side. The first said surface is tapered and presents a smaller inside diameter than the other said shoulder surface. It has been shown that, to enable fast, low-cost production of the said second shoulder surface, it must be tapered, and that suitable conical surfaces for this purpose are those on which the generating lines form an angle ranging from 5.degree. to 9.degree. in relation to a plane perpendicular to the bearing ring axis.
A shoulder surface of this shape, however, is not altogether suitable for ensuring correct shouldering of the sealing ring. In fact, it has been found that, owing to the deformable nature of the ring itself, the ring may, during operation, be deformed in such a way as to assume a tapered configuration, thus affecting pressure distribution between the lips on the sealing ring and the corresponding supporting surface on the bearing inner ring. Such deformation of the ring may therefore have a negative effect on its sealing performance, particularly in cases where the ring is provided with a pair of annular lips with a labyrinth in between them. In fact, such deformation may result in one of the lips coming away from the corresponding supporting surface, and a considerable alteration in the size of the labyrinth between the lips themselves.